Supported metal oxide catalysts are one of the major forms of materials used as heterogeneous catalysts. They are composed of an active material deposited on the surface of a high-surface area support, which the nominal purpose of achieving high dispersion of the active material. However, the support material may contribute to catalysis also, by providing or generating new active sites. With compositions spanning across the Periodic Table, supported metal oxide catalysts are found in industrial chemical processes, commercial applications, and environmental protection, such as automobile catalytic converters, NOx reduction from power plants, petroleum refining, drug manufacture, and petrochemicals processing.
The preparation method for these catalysts typically involves soaking the support metal oxide in a solution containing the solubilized precursors of the metal oxide to be supported. Drying causes the precursor to adsorb on the surface of the support metal oxide and calcination at high temperatures converts it to a metal oxide. This impregnation method ensures the active phase is exposed on the support surface and is commonly used to prepared commercial catalysts. This method has several drawbacks, namely: the amount of active phase that can be supported is relatively low (compared to precipitation, the other common method to industrial catalysts); the distribution of active phase throughout the catalyst may not be uniform; and the support material is typically composed of a random microstructure. Hence it is desired to provide a catalyst that avoids the shortcomings of the prior art.